JPH05298638A - Recording and reproducing device - Google Patents

Abstract

PURPOSE:To provide a recording and reproducing device unnecessary for rewinding a tape even at the time of tape ending and surely securing the recording the equivalent to a tape amt. regardless of a tape position. CONSTITUTION:This device is provided with a tape guide drum 1 which runs rotably with eight pieces of heads 21a-21h attached on a circumference in the same plane separated at an equal interval and with the magnetic tape wound round in the range of at least 330 deg., and a head switching means switching the head used for recording or reproducing at every 3/8 revolution of the guide drum 1. Then, each 1/2 field of a video signal is recorded or reproduced on the different area of the width direction of the magnetic tape 2 corresponding to the running direction of the magnetic tape 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention, like a video tape recorder (VTR), draws out a tape stretched in a tape cassette and slants the tape around a tape guide drum equipped with a rotary head. The present invention relates to a recording / reproducing apparatus that winds and travels in a state where a predetermined tape path is formed to record and reproduce a video signal, an audio signal, and the like.

[0002]

2. Description of the Related Art Recently, as a recording / reproducing apparatus of this type, a V
Although TR shows an extremely high penetration rate, consumers' needs are focused on reducing the size and weight of devices and increasing their functionality, and coexistence of both is becoming an important development factor.

As is well known, in this type of recording / reproducing apparatus, generally two or four heads for recording / reproducing video signals are rotatably mounted on a tape guide drum. , And, if there are four, 90 degrees apart in the same plane on the circumference. For example, in the case of 8 mm VTR format, the tape guide drum diameter is 40 mm for two heads and 26.
It is 7 mm, and the case of four heads suitable for reduction in size and weight has become the mainstream in recent years. Then, rotate the tape guide drum at high speed while running the tape,
One field of the signal is recorded on one continuous track, and the pattern is formed so that the recording tracks are adjacent to each other while sequentially switching the heads to be recorded.

At this time, the length of one track, that is, the video signal track of one field, is such that the tape guide drum having two heads is normally rotated at 1/2 the field frequency of the standard TV signal, 1 tape around
Since the recording is carried out in a state of being wrapped by 80 degrees, it is configured so as to correspond to approximately 1/2 of the circumference of the tape guide drum.

Therefore, when recording with four heads, the diameter of the tape guide drum may be 2/3 of the diameter of the tape guide drum with two heads, but the tape winding angle is 3/2 times. That is, it is necessary to ensure compatibility by winding and recording 270 degrees to perform recording and reproduction.

An example of a conventional recording / reproducing apparatus will be briefly described below with reference to the drawings. 10 is a block diagram of a tape guide drum used in a conventional recording / reproducing apparatus, FIG. 11 is a timing chart showing the recording method, and FIG. 12 is a recording pattern actually formed on the tape.

As shown in FIG. 10, on the tape guide drum 101, four heads 103a to 103d are rotatably provided on the same plane at intervals of 90 degrees. The diameter J of the tape guide drum 101 is about 26.7 mm as previously shown. The tape 102 is wound around the tape guide drum 101 by about 300 degrees, and a signal is recorded for 270 degrees of the tape. The tape 102 is wound around the tape guide drum 101 with a relative angle θ, and this θ is a fixed portion (not shown) of the tape guide drum 101.
It is also the angle of the lead (see FIG. 12) that serves as a running guide for the tape 102 provided on the above. Also, during recording and playback,
The tape guide drum 101 rotates counterclockwise (the direction indicated by the arrow), and the tape 102 runs in the same direction as this rotation direction.

A recording method by the recording / reproducing apparatus configured as described above will be specifically described with reference to FIGS. 10 and 11.

The tape guide drum 101 rotates at 3/4 times the standard TV frequency and 45 Hz in the case of the NTSC system (field frequency: 60 Hz). First, while the tape guide drum 101 rotates 3/4 (1
The first field signal A is recorded on the tape 102 by using the head 103a for 60 seconds). Thereafter, the heads 103b to 103d are used to sequentially record the field signals B to D without a time interval, and the head 103a is returned again to repeat the recording. Note that, in FIG. 11, the rectangle shown by the solid line is a case where each head actually records the field signal indicated by the alphabet in the drawing on the tape, and the number of the track recorded on the tape 102 is added to each head. is there. Further, the rectangle shown by the broken line is a case where the head and the tape are in contact with each other but no signal is transmitted or received.

As a result, the recording pattern formed on the tape 102 is determined from the angle θ of the lead formed on the tape guide drum 101 as shown in FIG.
Angle θ increased by the traveling speed in the direction of arrow X1
_The tracks 104a to 104d inclined by ₁ are sequentially arranged. Note that the traveling direction of each head is the arrow Y direction.

In general, in order to reduce crosstalk during reproduction, each head 103a is placed between adjacent tracks.
The gap azimuth of -10 3d is changed. That is, as indicated by the diagonal lines in FIG. 11, the head 103a,
Different gap azimuths are set between the head 103b and the heads 103b and 103d.

[0012]

However, in the above structure, since the tape is run in only one direction for recording / reproducing, for example, the recording / reproducing operation of the signal is completely completed in one tape cassette. If you try to record / play back again when the tape is almost at the end like at times, you have to rewind the tape to the initial position.
Moreover, since the time required for rewinding the tape is long, the operation efficiency during recording and reproduction is extremely poor. Alternatively, when recording or reproducing is performed as it is from the middle of the tape, there is a problem that the recording / reproducing time of the subsequent video signal is limited depending on the remaining amount of the tape in the tape cassette.

In consideration of such a conventional problem, the present invention does not require rewinding of the tape even at the end of the tape, and the recording / reproduction can surely guarantee the recording of the time corresponding to the tape amount regardless of the tape position. The purpose is to provide a device.

[0014]

According to a first aspect of the present invention, there is provided a rotatable head means having a plurality of magnetic heads for recording or reproducing a magnetic tape, and a video signal is recorded or recorded by the head means. When reproducing, a head switching unit that switches the magnetic head for each half field of the video signal and a tape running unit that can run the magnetic tape in both directions are provided. The recording / reproducing apparatus performs recording in a different width area of the width area divided into at least two in the width direction of the magnetic tape, with one half of the field of the video signal as one track according to the traveling direction.

According to the present invention of claim 2, 4n magnetic heads are mounted on the circumference of the same plane at equal intervals.
Magnetic tape is at least 360 x (4n-1) / (4
of the rotatable tape guide drum that travels while being wound in the range of (n) degrees, and (2n−
1) / (4n), a head switching unit that switches a magnetic head used for recording or reproducing every rotation, and recording or reproducing is performed in different regions in the width direction of the magnetic tape according to the running direction of the magnetic tape. , A recording / reproducing apparatus for performing 1/2 field of a video signal.

According to the present invention of claim 6, 4n magnetic heads are mounted on the circumference of the same plane at equal intervals.
Magnetic tape is at least 360 x (2n-1) / (2
of the rotatable tape guide drum that travels while being wound in the range of (n) degrees, and (2n−
1) / (4n), a head switching unit that switches a magnetic head used for recording or reproducing every rotation, and recording or reproducing is performed in different regions in the width direction of the magnetic tape according to the running direction of the magnetic tape. , A recording / reproducing apparatus for performing 1/2 field of a video signal.

[0017]

According to the present invention of claim 1, the tape running means runs the magnetic tape in the forward direction or the reverse direction, and the head switching means carries out the magnetic head of the head means for each half field of the video signal. The magnetic head is divided into at least two width areas in the width direction of the magnetic tape, with the half field of the video signal as one track according to the running direction of the magnetic tape. The video signal is recorded or reproduced.

According to the second aspect of the present invention, the magnetic tape is provided on the tape guide drum at least 360 × (4n-1) /
The tape is driven while being wound in the range of (4n) degrees, and the head switching means is (2n-1) / of the tape guide drum.
(4n) The magnetic head used for recording or reproduction is switched every rotation, and the magnetic head records half fields of the video signal in different areas in the width direction of the magnetic tape according to the running direction of the magnetic tape. Or play.

In a sixth aspect of the present invention, the magnetic tape is provided on the tape guide drum at least 360 × (2n-1) /
The tape guide drum travels while being wound in the range of (2n) degrees, and the head switching means moves (2n-1) / of the tape guide drum.
(4n) The magnetic head used for recording or reproduction is switched every rotation, and the magnetic head records half fields of the video signal in different areas in the width direction of the magnetic tape according to the running direction of the magnetic tape. Or play.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings showing its embodiments.

FIG. 1 is a block diagram of a tape guide drum used in a recording / reproducing apparatus according to the first embodiment of the present invention, and FIGS. 2, 3 and 4 are timing charts showing an example of the recording method. 5 is an example of a recording pattern on the tape.

As shown in FIG. 1, eight heads 21a to 21h are provided on the rotatable tape guide drum 1 on the same plane at intervals of 45 degrees. Those heads 2
1a to 21h are connected to a head switching unit (not shown) that switches when recording or reproducing a video signal. The diameter P of the tape guide drum 1 is set to 4/7 of the diameter of two heads, for example 8 mmVT
Approximately 22.9 m when recording in R format
m. The tape 2 is wound around the tape guide drum 1 by about 330 degrees, and the signal is recorded at 315 degrees, which is 7/4 times the normal winding angle of 180 degrees. As in the conventional example, the tape 2 is wound around the tape guide drum 1 with a relative angle θ, and the tape 2 is provided on a fixed portion (not shown) of the tape guide drum 1. It is also the angle of the lead (see FIG. 5) that serves as a travel guide for the. During recording and reproduction, the tape guide drum 1 rotates counterclockwise (arrow Y), and the tape 2 is moved in the same direction (arrow X1) or in the opposite direction (arrow X) by the tape running means (not shown).
Drive to 2).

The operation of the recording method by the recording / reproducing apparatus configured as described above will be specifically described.

First, the case of completely maintaining compatibility with the conventional recording / reproducing apparatus will be described with reference to FIGS. 1 and 2. The tape guide drum 1 has a standard TV frequency of 7 /
8 times, in case of NTSC system (field frequency: 60H
In the case of z), it rotates at 52.5 Hz. The first field signal A is recorded on the tape 2 using the head 21a while the tape guide drum 1 rotates 7/8 (1/60 seconds). Next, the field signal B is recorded using the head 21b without a time interval. After that, similarly, the heads 21c to 21h are used to sequentially record the field signals C to H, and the head 21a is returned again to repeat the recording. At this time, if the tape running speed is set to be the same as that of the conventional example, the recording pattern on the tape 2 becomes completely the same as that shown in FIG. 12, and compatibility with the conventional apparatus is maintained.

In this case, the running speed of the tape 2 is set to be the same as usual so that the recording tracks are adjacent to each other, but in order to reduce crosstalk during reproduction, the gap azimuth of each head is set between adjacent tracks. It is better to change it. That is, as indicated by the diagonal lines in FIG. 2, the heads 21a, 21c, 21e, 21g and the head 21b,
21d, 21f, and 21h are set to different gap azimuths.

Next, the case where recording is possible even when the tape 2 runs in both forward and reverse directions will be described. As shown in FIG. 1, the normal tape running direction is indicated by arrow X1 and the opposite direction is indicated by arrow X2.

First, the case where the tape 2 runs in the usual arrow X1 direction will be described with reference to FIGS.
The rotation frequency of the tape guide drum 1 is 3/4 times the standard TV frequency, 45 Hz if the NTSC system is taken as an example.
Set to. Further, the running speed of the tape 2 is doubled as compared with the case where the compatibility described above is maintained. Then, while the tape guide drum 1 rotates 3/8 times (1/120 seconds), the field signal A divided in half by the head 21a is used.
Record 1 on tape 2. Next, the field signal A2 divided into the remaining ½ is recorded using the head 21f without a time interval. After that, the head 21
c, 21h, 21e, 21b, 21g, 21d are used to sequentially divide the field signals B1 to D2 into 1/2.
Is recorded on tape 2. Then, it returns to the head 21a again, and the field signal E1 divided in half is supplied to the tape 2
Record above and repeat recording in the same way. As a result, the recording pattern formed on the tape 2 is such that a signal is recorded only on the lower half of the tape 2 in the width direction as shown in FIG. 5, and the angle θ of the lead formed on the tape guide drum 1 , Tracks 22a-2 inclined by an angle α ₁ increased by the traveling speed of the tape 2 in the direction of arrow X1.
2h will be lined up in sequence.

Similar to the conventional example, the rectangle shown by the solid line in FIG. 3 is a case where each of the heads 21a to 21h actually records the divided field signal indicated by the alphabet in the figure on the tape 2, and the tape 2 is recorded on each tape. It is accompanied by the track number recorded above. Further, the rectangle shown by the broken line is a case where the head 21 and the tape 2 are in contact with each other but no signal is transmitted or received.

Next, the case where the tape 2 runs in the direction of the arrow X2, which is opposite to the normal direction, will be described with reference to FIGS. Rotation frequency of tape guide drum 1 and tape 2
The traveling speed of is set to the same value as described above. After the rotating head 21a and the tape 2 start contacting each other and the tape guide drum 1 rotates 4/8 times, the head 21a is used for 1/2 during the next 3/8 rotation (1/120 seconds). The field signal A1 divided into two is recorded on the tape 2. Next, similarly, the head 21f is used to record the remaining half-divided field signal A2. After that,
Heads 21c, 21h, 21e, 21b, 21g, 21
field signal B divided in half by using d
Record 1-D2 on tape 2. And again head 2
Returning to 1a, the recording is repeated in the same manner. The recording pattern at this time is such that signals are recorded only in the upper half of the tape 2 in the width direction as shown in FIG. Further, the tracks 23a to 23h on the tape 2 are recorded on the tape 2 at an angle α2 which is smaller than the lead angle θ of the tape guide drum 1 described above by the traveling speed of the tape 2 in the arrow direction. It

However, at this time, a portion where no signal is recorded occurs between the tracks 22a to 22h and the tracks 23a to 23h in the widthwise central portion of the tape 2. This corresponds to a signal amount corresponding to 1/8 rotation of the tape guide drum 1. Therefore, the tape use efficiency in this embodiment is about 6/7 that of the normal recording method.

In this case, the running speed of the tape 2 is set to twice the normal speed so that the tracks 22a to 22h and 23a to 23h are adjacent to each other, but the tracks adjacent to each other are reduced in order to reduce crosstalk during reproduction. It is desirable to change the gap azimuth of the recording head. To this end, first, of the heads 21a to 21h provided on the circumference of the tape guide drum 1, so that the gap azimuths between adjacent tracks are different when normal recording is performed,
In order to make the gaps azimuths of the heads adjacent to each other different and to maintain the compatibility between the devices, the gaps are set to 9 mm from each other.
The gap azimuths of the heads arranged at intervals of 0 degrees may be equalized. In order to make the gap azimuths between adjacent tracks different when recording and reproduction are possible even when the tape running direction is changed, the gaps azimuths of the heads arranged at 135 ° intervals are made different. This is included in the conditions for normal recording. That is, as shown in FIG.
1c, 21e, 21g and heads 21b, 21d, 21
Different gap azimuths are set between f and 21h.

As described above, according to the present embodiment, it is possible to sequentially record signals only on one half of the width direction of the tape while maintaining the compatibility with the conventional recording / reproducing apparatus. Therefore, even at the end of the tape, recording and reproduction can be performed without rewinding the tape simply by reversing the tape running direction. In addition, regardless of the position of the tape, the recording of the video signal for the time corresponding to the tape amount can be guaranteed without fail,
Furthermore, it is possible to provide a recording / reproducing apparatus that enables endless recording / reproducing.

In the above embodiment, the recording / reproducing apparatus is configured to be compatible with the conventional recording / reproducing method, but the present invention is not limited to this and may be configured as a dedicated recording / reproducing apparatus.

Further, in the above embodiment, the number of magnetic heads of the tape guide drum which is the head means is eight,
Not limited to this, any integral multiple of 4 may be used. Alternatively, if the recording / reproducing apparatus is a dedicated one, it is also possible to use a plurality of two or more.

FIG. 6 is a block diagram of the tape guide drum of the second embodiment according to the present invention. FIG. 7 is a timing chart showing the recording method, and FIG. 8 is a recording pattern on the tape.

As shown in FIG. 6, on the rotatable tape guide drum 1, eight heads 31a to 31h are provided on the same plane at intervals of 45 degrees. The diameter Q of the tape guide drum 1 is set to 2/3 of the diameter in the case of two heads, which is about 26.7 mm, which is the same as the conventional example.
The tape 2 is wound around the tape guide drum 1 by about 300 degrees, and a signal is recorded for 270 degrees of the tape. The tape 2 is wound around the tape guide drum 1 while being inclined by the same relative angle θ as in the conventional example.
Further, the tape 2 is fed by a tape running means (not shown).
The heads 31a to 31h are connected to head switching means (not shown) so that they can travel in the forward or reverse direction.

A recording method by the recording / reproducing apparatus configured as above will be described with reference to FIGS. 6 and 7.

First, in order to maintain the compatibility with the conventional recording / reproducing apparatus, the tape guide drum 1 is used as a standard TV.
Recording and reproduction are performed by exactly the same recording method as in the conventional example using four heads 31a, 31c, 31e and 31g while rotating at 3/4 times the frequency, that is, 45 Hz.

Next, the case where recording is possible even when the tape 2 runs in both forward and reverse directions will be described. The recording pattern at this time is shown in FIG. 8, and the normal tape running direction is indicated by arrow X1 and the opposite direction is indicated by arrow X2. First, consider a case where the tape 2 travels in the normal arrow X1 direction. The tape guide drum 1 rotates at 45 Hz as usual. And the tape guide drum 1
While the head rotates 3/8 (1/120 seconds), the head 31
The field signal A1 divided into ½ using a is recorded on the tape 2. Next, the head 31f is used to record the remaining half-divided field signal A2.
After that, the heads 31c, 31h, 31e, 31b, 3
The field signals B1 to D2, which are sequentially divided in half, are recorded on the tape 2 by using 1g and 31d. And
Returning to the head 31a again, recording is repeated in the same manner.
The recording pattern at this time is such that signals are recorded only in the lower half of the tape 2 in the width direction as shown in FIG.
Further, the tracks 32a to 32h on the tape 2 are located closer to the tape 2 than the lead angle θ of the tape guide drum 1 described above.
Inclination increased by the traveling speed in the arrow X1 direction β
Recorded at an angle of 1.

Next, the tape 2 indicates the arrow X2 opposite to the normal direction.
Think about when traveling in the direction. The rotation frequency of the tape guide drum 1 similarly rotates at 45 Hz. After the rotating head 31a and the tape 2 start contacting each other and the tape guide drum 1 rotates 3/8, during the next 3/8 rotation (1/120 seconds), the head 31a is used for 1/2.
The divided field signal is recorded on the tape 2.
Next, similarly, the other half of the field signal divided into ½ is recorded using the head 31f. After that, the heads 31c, 31h, 31e, 31b, 31g, and 31d are used to record the field signal sequentially divided into ½ on the tape 2. Finally, the head 31a is returned again, and recording is repeated in the same manner. The recording pattern at this time is
As shown in FIG. 8, the signal is recorded only on the upper half of the tape 2 in the width direction. Further, the track 32 on the tape 2 is recorded at an angle of β2, which is smaller than the lead angle θ of the tape guide drum 1 by the traveling speed of the tape 2 in the direction of the arrow X2.

At this time, at the center of the tape 2 in the width direction, the ends of the tracks 32a-32h and the tracks 33a-
There is a risk that the beginning of 33h will overlap. However, as described above, since the tape 2 is wound around the tape guide drum 1 in excess of the rotation angle required for each head to record a signal, the recording timings of the tracks 33a to 33h are slightly shifted, so that It is possible to avoid overlapping. Therefore, since there is almost no gap in the central portion of the tape 2 as shown in the first embodiment, the tape usage efficiency in this embodiment is almost equal to that in the normal recording method.

The running speed of the tape 2 is the same as that of each track 3
Although 2a to 32h and 33a to 33h are set to be twice as normal as usual, it is preferable to change the gap azimuth of the heads recording adjacent tracks in order to reduce crosstalk during reproduction. To this end, first, the tape guide drum 1 is set so that the gap azimuth between adjacent tracks is different when normal recording is performed.
Of the heads 31a to 31h provided on the circumference of each of the heads 31a to 31h, the heads 31a to 31h have different gaps azimuths arranged at intervals of 90 degrees from each other, and in order to maintain compatibility between the devices, the heads 180a to The gaps azimuths of the heads arranged at an interval of 1 degree may be equal. In order to make the gap azimuths between adjacent tracks different when recording and reproduction are possible even if the tape running direction is changed, it is only necessary to make the gaps azimuths of the heads adjacent to each other different. That is, the head 31a,
31e and heads 31c and 31g and heads 31b and 31
Different gap azimuths are set between d, 31f, and 31h.

As described above, according to the present embodiment, the signals can be sequentially recorded on only one half of the width direction of the tape, and almost the entire width direction of the tape is used for recording the signals. Therefore, in addition to the effects of the first embodiment, it is possible to provide a recording / reproducing apparatus that achieves the same tape usage efficiency as the conventional one.

In the above embodiment, the running speed of the tape 2 is set to twice the normal speed, but instead of this, the tape 2 is used.
The traveling speed may be set to be higher than twice the normal traveling speed. In this case, as shown in FIG. 9, a constant gap, that is, a guard band, between the tracks on the tape 2 is formed.
Therefore, the crosstalk at the time of reproduction becomes extremely small, and a recorded and reproduced image with higher quality can be obtained.

[0045]

As is apparent from the above description, according to the present invention, there is no need to rewind the tape at the end of the tape.
Further, there is an advantage that recording for a time corresponding to the tape amount can be surely guaranteed regardless of the tape position.

Further, there is an advantage that recording and reproduction can be performed endlessly.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a tape guide drum according to a first embodiment of the present invention.

FIG. 2 is a timing chart showing a normal recording method in the embodiment.

FIG. 3 is a timing chart showing a recording method of tape running in the forward direction in the embodiment.

FIG. 4 is a timing chart showing a recording method of tape running in the reverse direction in the embodiment.

FIG. 5 is an explanatory diagram of a recording pattern on a tape according to the example.

FIG. 6 is a configuration diagram of a tape guide drum of a second embodiment according to the present invention.

FIG. 7 is a timing chart showing a recording method in a second embodiment.

FIG. 8 is an explanatory diagram of recording patterns on a tape according to a second embodiment.

FIG. 9 is an explanatory diagram of a recording pattern on a tape when the tape speed is set to be more than double in the second embodiment.

FIG. 10 is a configuration diagram of a tape guide drum of a conventional recording / reproducing apparatus.

FIG. 11 is a timing chart showing a conventional recording method.

FIG. 12 is an explanatory diagram of a recording pattern on a conventional tape.

[Explanation of symbols]

 1 tape guide drum 2 tapes 21a to 21h heads 22a to 22h, 23a to 23h tracks 31a to 31h heads 32a to 32h, 33a to 33h tracks 101 tape guide drums 102 tapes 103a to 103d heads

Claims (10)

[Claims] 1. A rotatable head means having a plurality of magnetic heads for recording or reproducing a magnetic tape,
When recording or reproducing a video signal by the head means, head switching means for switching the magnetic head for each half field of the video signal and tape running means capable of running the magnetic tape in both directions are provided. The recording or reproducing of the video signal is divided into at least two in the width direction of the magnetic tape with one half of the field of the video signal as one track according to the running direction of the magnetic tape. A recording / reproducing apparatus, wherein the recording / reproducing apparatus is performed in different width areas. 2. The 4n magnetic heads are mounted on the circumference of the same plane at equal intervals, and the magnetic tape is wound around at least 360 × (4n−1) / (4n) degrees and runs. And a head switching means for switching the magnetic head used for recording or reproduction every (2n-1) / (4n) rotations of the tape guide drum. A recording / reproducing apparatus characterized in that, according to the running direction of the magnetic tape, the video signal is recorded in different areas in the width direction of the magnetic tape for each half field of the video signal. 3. The head switching means further comprises: (4n-1) / (4n) of the tape guide drum when sequentially recording the video signal one field at a time on the magnetic tape running in the forward direction. The recording / reproducing apparatus according to claim 2, wherein the magnetic head used for recording or reproducing can be switched for each rotation. 4. The 4n magnetic heads have different gap azimuths of the magnetic heads adjacent to each other, and the gap azimuths of the magnetic heads arranged at intervals of 180 / n degrees are equal to each other. The recording / reproducing apparatus according to claim 2. 5. A tape guide drum of (4n-1) /
The rotation frequency of the magnetic head when the magnetic head is switched every (4n) revolutions is f _1, and the magnetic field when the magnetic head is switched every (2n−1) / (4n) revolutions of the tape guide drum. When the rotation frequency of the head is f ₂ and the field frequency is f ₀ , f ₁ = f ₀ × (4n−1) / (4n) f ₂ = f ₀ × (2n−1) / (2n) The recording / reproducing apparatus according to claim 3, wherein 6. The 4n magnetic heads are mounted on the circumference of the same plane at equal intervals, and the magnetic tape is wound around at least 360 × (2n−1) / (2n) degrees and runs. And a head switching means for switching the magnetic head used for recording or reproduction every (2n-1) / (4n) rotations of the tape guide drum. A recording / reproducing apparatus characterized in that, according to the running direction of the magnetic tape, the video signal is recorded in different areas in the width direction of the magnetic tape for each half field of the video signal. 7. The running speed of the magnetic tape is such that, when V ₁ is the speed when recording or reproducing one field of the video signal as one track, 1/2 field of the video signal is recorded as one track or 7. The recording / reproducing apparatus according to claim 1, wherein V ₂ ≧ 2 × V ₁ where V ₂ is a speed for reproducing. 8. The head switching means further comprises: (2n-1) / (2n) of the tape guide drum when sequentially recording the video signal one field at a time on the magnetic tape running in the forward direction. 7. The recording / reproducing apparatus according to claim 6, wherein the magnetic head used for recording or reproduction can be switched for each rotation. 9. The 4n magnetic heads have different gap azimuths of the magnetic heads adjacent to each other, and have the same gap azimuths of the magnetic heads arranged at intervals of 360 / n degrees, and 180 / n of each other. 7. The recording / reproducing apparatus according to claim 6, wherein at least one set of gap azimuths of the magnetic heads arranged at an interval of 1 degree is different. 10. A tape guide drum of (2n-1) /
The rotation frequency of the magnetic head when the magnetic head is switched every (2n) revolutions is f _1, and the magnetic frequency when the magnetic head is switched every (2n−1) / (4n) revolutions of the tape guide drum. the rotational frequency of the head and f _2, when the field frequency is f _0, the recording and reproducing according to claim 8, wherein the _{f 1 = f 2 = f 0} × (2n-1) is / (2n) apparatus.